Leakage between two adjoining pieces of plastic pipe after the spigot end of one pipe is inserted into the bell end of another pipe is traditionally prevented by means of a rubber sealing gasket that is seated in the pipe bell. Today, more than 90% of polyvinylchloride (PVC) pipes in the North America, whether intended for pressurized or non-pressurized applications, include “locked-in” gaskets, which are commonly referred to Rieber gaskets. A Rieber gasket consists of a continuous steel band either externally or internally bonded to an elastomer annular body. The Rieber gasket is incorporated into the pipe during the belling process and locked into place within an annular groove of the bell. The steel band functions to prevent the gasket from becoming dislodged from the bell.
Rieber gaskets offer very little resistance to axial separation of plastic pipe joints upon fluid pressurization of the joints. To overcome this shortcoming of Rieber joints, restraint harnesses are often used for preventing the withdrawal of plastic spigots from plastic bells. Restraint harnesses consist of two split serrated restraint rings, one secured about the spigot end of one pipe and the other secured about the bell end of another pipe. The restraint rings are fastened into a harness by an array of thrust rods, which are tightened against the ring thereby pressing the pipes together. While restraint harnesses prevent axial separation of plastic pipe joints, the cost of the harnesses and time required to install the harness limit their use.